PHP生成自适应大小的缩略图类及使用方法分享(2)

if ( function_exists ( 'file_get_contents' ) )
    {
      $str = @file_get_contents ( $image_file );
      if ( ! $str )
      {
        $err = sprintf( E_002, $image_file );
        trigger_error( $err, E_USER_ERROR );
      }
      return $str;
    }

$f = fopen ( $image_file, 'rb' );
    if ( ! $f )
    {
      $err = sprintf( E_002, $image_file );
      trigger_error( $err, E_USER_ERROR );
    }
    $fsz = @filesize ( $image_file );
    if ( ! $fsz )
      $fsz = MAX_IMG_SIZE;
    $str = fread ( $f, $fsz );
    fclose ( $f );

return $str;

}

/*
    Description:
      Loads image from file.
    Prototype:
      resource LoadImage ( string image_file, int &image_width, int &image_height )
    Parameters:
      image_file - filename of image
      image_width - width of loaded image
      image_height - height of loaded image
    Return:
      Image identifier representing the image obtained from the given file.
  */
  function LoadImage ( $image_file, &$image_width, &$image_height )
  {

$image_width = 0;
    $image_height = 0;

$image_data = $this->GetImageStr( $image_file );

$image = imagecreatefromstring ( $image_data );
    if ( ! $image )
    {
      $err = sprintf( E_003, $image_file );
      trigger_error( $err, E_USER_ERROR );
    }

$image_width = imagesx ( $image );
    $image_height = imagesy ( $image );

return $image;

}

/*
    Description:
      Calculates thumbnail image sizes from source image width and height.
    Prototype:
      array GetThumbSize ( int src_width, int src_height )
    Parameters:
      src_width - width of source image
      src_height - height of source image
    Return:
      An array with 2 elements. Index 0 contains the width of thumbnail image
      and index 1 contains the height.
  */
  function GetThumbSize ( $src_width, $src_height )
  {

$max_width = $this->max_width;
    $max_height = $this->max_height;

$x_ratio = $max_width / $src_width;
    $y_ratio = $max_height / $src_height;

$is_small = ( $src_width <= $max_width && $src_height <= $max_height );

if ( ! $this->fit_to_max && $is_small )
    {
      $dest_width = $src_width;
      $dest_height = $src_height;
    }
    elseif ( $x_ratio * $src_height < $max_height )
    {
      $dest_width = $max_width;
      $dest_height = ceil ( $x_ratio * $src_height );
    }
    else
    {
      $dest_width = ceil ( $y_ratio * $src_width );
      $dest_height = $max_height;
    }

return array ( $dest_width, $dest_height );

}

/*
    Description:
      Adds logo image to thumbnail.
    Prototype:
      void AddLogo ( int thumb_width, int thumb_height, resource &thumb_img )
    Parameters:
      thumb_width - width of thumbnail image
      thumb_height - height of thumbnail image
      thumb_img - thumbnail image identifier
  */
  function AddLogo ( $thumb_width, $thumb_height, &$thumb_img )
  {

extract ( $this->logo );

$logo_image = $this->LoadImage ( $file, $logo_width, $logo_height );

if ( $vert_pos == POS_CENTER )
      $y_pos = ceil ( $thumb_height / 2 - $logo_height / 2 );
    elseif ($vert_pos == POS_BOTTOM)
      $y_pos = $thumb_height - $logo_height;
    else
      $y_pos = 0;